8 our $AUTHORITY = 'cpan:STEVAN';
10 use Scalar::Util 'blessed', 'reftype';
12 use Sub::Name 'subname';
13 use B 'svref_2object';
19 use Moose::Meta::Class;
20 use Moose::Meta::TypeConstraint;
21 use Moose::Meta::TypeCoercion;
22 use Moose::Meta::Attribute;
23 use Moose::Meta::Instance;
25 use Moose::Meta::Role;
28 use Moose::Util::TypeConstraints;
34 my ( $class, $base_class, $metaclass ) = @_;
35 $base_class = $class unless defined $base_class;
36 $metaclass = 'Moose::Meta::Class' unless defined $metaclass;
39 "The Metaclass $metaclass must be a subclass of Moose::Meta::Class."
40 unless $metaclass->isa('Moose::Meta::Class');
42 # make a subtype for each Moose class
43 subtype $class => as 'Object' => where { $_->isa($class) } =>
44 optimize_as { blessed( $_[0] ) && $_[0]->isa($class) }
45 unless find_type_constraint($class);
48 if ( $class->can('meta') ) {
50 # this is the case where the metaclass pragma
51 # was used before the 'use Moose' statement to
52 # override a specific class
53 $meta = $class->meta();
54 ( blessed($meta) && $meta->isa('Moose::Meta::Class') )
55 || confess "You already have a &meta function, but it does not return a Moose::Meta::Class";
59 # this is broken currently, we actually need
60 # to allow the possiblity of an inherited
61 # meta, which will not be visible until the
62 # user 'extends' first. This needs to have
63 # more intelligence to it
64 $meta = $metaclass->initialize($class);
68 # re-initialize so it inherits properly
69 $metaclass->initialize( blessed( $_[0] ) || $_[0] );
74 # make sure they inherit from Moose::Object
75 $meta->superclasses($base_class)
76 unless $meta->superclasses();
82 return subname 'Moose::extends' => sub (@) {
83 confess "Must derive at least one class" unless @_;
84 Class::MOP::load_class($_) for @_;
86 # this checks the metaclass to make sure
87 # it is correct, sometimes it can get out
88 # of sync when the classes are being built
89 my $meta = $class->meta->_fix_metaclass_incompatability(@_);
90 $meta->superclasses(@_);
95 return subname 'Moose::with' => sub (@) {
97 confess "Must specify at least one role" unless @roles;
98 Class::MOP::load_class($_) for @roles;
99 $class->meta->_apply_all_roles(@roles);
104 return subname 'Moose::has' => sub ($;%) {
105 my ( $name, %options ) = @_;
106 my $attrs = ( ref($name) eq 'ARRAY' ) ? $name : [ ($name) ];
107 $class->meta->_process_attribute( $_, %options ) for @$attrs;
112 return subname 'Moose::before' => sub (@&) {
114 my $meta = $class->meta;
115 $meta->add_before_method_modifier( $_, $code ) for @_;
120 return subname 'Moose::after' => sub (@&) {
122 my $meta = $class->meta;
123 $meta->add_after_method_modifier( $_, $code ) for @_;
128 return subname 'Moose::around' => sub (@&) {
130 my $meta = $class->meta;
131 $meta->add_around_method_modifier( $_, $code ) for @_;
138 $SUPER_SLOT{$CALLER} = \*{"${CALLER}::super"};
140 return subname 'Moose::super' => sub { };
144 return subname 'Moose::override' => sub ($&) {
145 my ( $name, $method ) = @_;
146 $class->meta->add_override_method_modifier( $name => $method );
153 $INNER_SLOT{$CALLER} = \*{"${CALLER}::inner"};
155 return subname 'Moose::inner' => sub { };
159 return subname 'Moose::augment' => sub (@&) {
160 my ( $name, $method ) = @_;
161 $class->meta->add_augment_method_modifier( $name => $method );
165 return \&Carp::confess;
168 return \&Scalar::Util::blessed;
172 my $exporter = Sub::Exporter::build_exporter(
174 exports => \%exports,
175 groups => { default => [':all'] }
179 # 1 extra level because it's called by import so there's a layer of indirection
183 ref $_[1] && defined $_[1]->{into}
185 : ref $_[1] && defined $_[1]->{into_level}
186 ? caller($offset + $_[1]->{into_level})
191 $CALLER = _get_caller(@_);
196 # we should never export to main
197 return if $CALLER eq 'main';
199 init_meta( $CALLER, 'Moose::Object' );
206 my $class = _get_caller(@_);
208 # loop through the exports ...
209 foreach my $name ( keys %exports ) {
212 if ( defined &{ $class . '::' . $name } ) {
213 my $keyword = \&{ $class . '::' . $name };
215 # make sure it is from Moose
217 eval { svref_2object($keyword)->GV->STASH->NAME };
219 next if $pkg_name ne 'Moose';
221 # and if it is from Moose then undef the slot
222 delete ${ $class . '::' }{$name};
229 ## make 'em all immutable
231 $_->meta->make_immutable(
232 inline_constructor => 0,
233 inline_accessors => 1, # these are Class::MOP accessors, so they need inlining
236 'Moose::Meta::Attribute',
237 'Moose::Meta::Class',
238 'Moose::Meta::Instance',
240 'Moose::Meta::TypeConstraint',
241 'Moose::Meta::TypeConstraint::Union',
242 'Moose::Meta::TypeConstraint::Parameterized',
243 'Moose::Meta::TypeCoercion',
245 'Moose::Meta::Method',
246 'Moose::Meta::Method::Accessor',
247 'Moose::Meta::Method::Constructor',
248 'Moose::Meta::Method::Destructor',
249 'Moose::Meta::Method::Overriden',
252 'Moose::Meta::Role::Method',
253 'Moose::Meta::Role::Method::Required',
264 Moose - A complete modern object system for Perl 5
269 use Moose; # automatically turns on strict and warnings
271 has 'x' => (is => 'rw', isa => 'Int');
272 has 'y' => (is => 'rw', isa => 'Int');
285 has 'z' => (is => 'rw', isa => 'Int');
287 after 'clear' => sub {
294 Moose is an extension of the Perl 5 object system.
296 =head2 Another object system!?!?
298 Yes, I know there has been an explosion recently of new ways to
299 build object's in Perl 5, most of them based on inside-out objects
300 and other such things. Moose is different because it is not a new
301 object system for Perl 5, but instead an extension of the existing
304 Moose is built on top of L<Class::MOP>, which is a metaclass system
305 for Perl 5. This means that Moose not only makes building normal
306 Perl 5 objects better, but it also provides the power of metaclass
309 =head2 Is this for real? Or is this just an experiment?
311 Moose is I<based> on the prototypes and experiments I did for the Perl 6
312 meta-model. However, Moose is B<NOT> an experiment/prototype; it is for B<real>.
314 =head2 Is this ready for use in production?
316 Yes, I believe that it is.
318 Moose has been used successfully in production environemnts by several people
319 and companies (including the one I work for). There are Moose applications
320 which have been in production with little or no issue now for over a year.
321 I consider it highly stable and we are commited to keeping it stable.
323 Of course, in the end, you need to make this call yourself. If you have
324 any questions or concerns, please feel free to email me, or even the list
325 or just stop by #moose and ask away.
327 =head2 Is Moose just Perl 6 in Perl 5?
329 No. While Moose is very much inspired by Perl 6, it is not itself Perl 6.
330 Instead, it is an OO system for Perl 5. I built Moose because I was tired of
331 writing the same old boring Perl 5 OO code, and drooling over Perl 6 OO. So
332 instead of switching to Ruby, I wrote Moose :)
334 =head2 Moose Extensions
336 The L<MooseX::> namespace is the official place to find Moose extensions.
337 There are a number of these modules out on CPAN right now the best way to
338 find them is to search for MooseX:: on search.cpan.org.
340 =head1 BUILDING CLASSES WITH MOOSE
342 Moose makes every attempt to provide as much convenience as possible during
343 class construction/definition, but still stay out of your way if you want it
344 to. Here are a few items to note when building classes with Moose.
346 Unless specified with C<extends>, any class which uses Moose will
347 inherit from L<Moose::Object>.
349 Moose will also manage all attributes (including inherited ones) that are
350 defined with C<has>. And (assuming you call C<new>, which is inherited from
351 L<Moose::Object>) this includes properly initializing all instance slots,
352 setting defaults where appropriate, and performing any type constraint checking
355 =head1 EXPORTED FUNCTIONS
357 Moose will export a number of functions into the class's namespace which
358 may then be used to set up the class. These functions all work directly
359 on the current class.
365 This is a method which provides access to the current class's metaclass.
367 =item B<extends (@superclasses)>
369 This function will set the superclass(es) for the current class.
371 This approach is recommended instead of C<use base>, because C<use base>
372 actually C<push>es onto the class's C<@ISA>, whereas C<extends> will
373 replace it. This is important to ensure that classes which do not have
374 superclasses still properly inherit from L<Moose::Object>.
376 =item B<with (@roles)>
378 This will apply a given set of C<@roles> to the local class. Role support
379 is currently under heavy development; see L<Moose::Role> for more details.
381 =item B<has $name =E<gt> %options>
383 This will install an attribute of a given C<$name> into the current class.
384 The C<%options> are the same as those provided by
385 L<Class::MOP::Attribute>, in addition to the list below which are provided
386 by Moose (L<Moose::Meta::Attribute> to be more specific):
390 =item I<is =E<gt> 'rw'|'ro'>
392 The I<is> option accepts either I<rw> (for read/write) or I<ro> (for read
393 only). These will create either a read/write accessor or a read-only
394 accessor respectively, using the same name as the C<$name> of the attribute.
396 If you need more control over how your accessors are named, you can use the
397 I<reader>, I<writer> and I<accessor> options inherited from
398 L<Class::MOP::Attribute>.
400 =item I<isa =E<gt> $type_name>
402 The I<isa> option uses Moose's type constraint facilities to set up runtime
403 type checking for this attribute. Moose will perform the checks during class
404 construction, and within any accessors. The C<$type_name> argument must be a
405 string. The string may be either a class name or a type defined using
406 Moose's type definition features. (Refer to L<Moose::Util::TypeConstraints>
407 for information on how to define a new type, and how to retrieve type meta-data).
409 =item I<coerce =E<gt> (1|0)>
411 This will attempt to use coercion with the supplied type constraint to change
412 the value passed into any accessors or constructors. You B<must> have supplied
413 a type constraint in order for this to work. See L<Moose::Cookbook::Recipe5>
416 =item I<does =E<gt> $role_name>
418 This will accept the name of a role which the value stored in this attribute
419 is expected to have consumed.
421 =item I<required =E<gt> (1|0)>
423 This marks the attribute as being required. This means a I<defined> value must be
424 supplied during class construction, and the attribute may never be set to
425 C<undef> with an accessor.
427 =item I<weak_ref =E<gt> (1|0)>
429 This will tell the class to store the value of this attribute as a weakened
430 reference. If an attribute is a weakened reference, it B<cannot> also be
433 =item I<lazy =E<gt> (1|0)>
435 This will tell the class to not create this slot until absolutely necessary.
436 If an attribute is marked as lazy it B<must> have a default supplied.
438 =item I<auto_deref =E<gt> (1|0)>
440 This tells the accessor whether to automatically dereference the value returned.
441 This is only legal if your C<isa> option is either C<ArrayRef> or C<HashRef>.
443 =item I<metaclass =E<gt> $metaclass_name>
445 This tells the class to use a custom attribute metaclass for this particular
446 attribute. Custom attribute metaclasses are useful for extending the
447 capabilities of the I<has> keyword: they are the simplest way to extend the MOP,
448 but they are still a fairly advanced topic and too much to cover here. I will
449 try and write a recipe on them soon.
451 The default behavior here is to just load C<$metaclass_name>; however, we also
452 have a way to alias to a shorter name. This will first look to see if
453 B<Moose::Meta::Attribute::Custom::$metaclass_name> exists. If it does, Moose
454 will then check to see if that has the method C<register_implemenetation>, which
455 should return the actual name of the custom attribute metaclass. If there is no
456 C<register_implemenetation> method, it will fall back to using
457 B<Moose::Meta::Attribute::Custom::$metaclass_name> as the metaclass name.
459 =item I<trigger =E<gt> $code>
461 The I<trigger> option is a CODE reference which will be called after the value of
462 the attribute is set. The CODE ref will be passed the instance itself, the
463 updated value and the attribute meta-object (this is for more advanced fiddling
464 and can typically be ignored). You B<cannot> have a trigger on a read-only
467 =item I<handles =E<gt> ARRAY | HASH | REGEXP | ROLE | CODE>
469 The I<handles> option provides Moose classes with automated delegation features.
470 This is a pretty complex and powerful option. It accepts many different option
471 formats, each with its own benefits and drawbacks.
473 B<NOTE:> This feature is no longer experimental, but it may still have subtle
474 bugs lurking in the deeper corners. If you think you have found a bug, you
475 probably have, so please report it to me right away.
477 B<NOTE:> The class being delegated to does not need to be a Moose based class,
478 which is why this feature is especially useful when wrapping non-Moose classes.
480 All I<handles> option formats share the following traits:
482 You cannot override a locally defined method with a delegated method; an
483 exception will be thrown if you try. That is to say, if you define C<foo> in
484 your class, you cannot override it with a delegated C<foo>. This is almost never
485 something you would want to do, and if it is, you should do it by hand and not
488 You cannot override any of the methods found in Moose::Object, or the C<BUILD>
489 and C<DEMOLISH> methods. These will not throw an exception, but will silently
490 move on to the next method in the list. My reasoning for this is that you would
491 almost never want to do this, since it usually breaks your class. As with
492 overriding locally defined methods, if you do want to do this, you should do it
493 manually, not with Moose.
495 You do not I<need> to have a reader (or accessor) for the attribute in order
496 to delegate to it. Moose will create a means of accessing the value for you,
497 however this will be several times B<less> efficient then if you had given
498 the attribute a reader (or accessor) to use.
500 Below is the documentation for each option format:
506 This is the most common usage for I<handles>. You basically pass a list of
507 method names to be delegated, and Moose will install a delegation method
512 This is the second most common usage for I<handles>. Instead of a list of
513 method names, you pass a HASH ref where each key is the method name you
514 want installed locally, and its value is the name of the original method
515 in the class being delegated to.
517 This can be very useful for recursive classes like trees. Here is a
518 quick example (soon to be expanded into a Moose::Cookbook::Recipe):
523 has 'node' => (is => 'rw', isa => 'Any');
528 default => sub { [] }
536 parent_node => 'node',
537 siblings => 'children',
541 In this example, the Tree package gets C<parent_node> and C<siblings> methods,
542 which delegate to the C<node> and C<children> methods (respectively) of the Tree
543 instance stored in the C<parent> slot.
547 The regexp option works very similar to the ARRAY option, except that it builds
548 the list of methods for you. It starts by collecting all possible methods of the
549 class being delegated to, then filters that list using the regexp supplied here.
551 B<NOTE:> An I<isa> option is required when using the regexp option format. This
552 is so that we can determine (at compile time) the method list from the class.
553 Without an I<isa> this is just not possible.
557 With the role option, you specify the name of a role whose "interface" then
558 becomes the list of methods to handle. The "interface" can be defined as; the
559 methods of the role and any required methods of the role. It should be noted
560 that this does B<not> include any method modifiers or generated attribute
561 methods (which is consistent with role composition).
565 This is the option to use when you really want to do something funky. You should
566 only use it if you really know what you are doing, as it involves manual
569 This takes a code reference, which should expect two arguments. The first is the
570 attribute meta-object this I<handles> is attached to. The second is the
571 metaclass of the class being delegated to. It expects you to return a hash (not
572 a HASH ref) of the methods you want mapped.
578 =item B<has +$name =E<gt> %options>
580 This is variation on the normal attibute creator C<has> which allows you to
581 clone and extend an attribute from a superclass. Here is a quick example:
589 default => 'Hello, I am a Foo'
597 has '+message' => (default => 'Hello I am My::Foo');
599 What is happening here is that B<My::Foo> is cloning the C<message> attribute
600 from its parent class B<Foo>, retaining the C<is =E<gt> 'rw'> and C<isa =E<gt>
601 'Str'> characteristics, but changing the value in C<default>.
603 This feature is restricted somewhat, so as to try and force at least I<some>
604 sanity into it. You are only allowed to change the following attributes:
610 Change the default value of an attribute.
614 Change whether the attribute attempts to coerce a value passed to it.
618 Change if the attribute is required to have a value.
620 =item I<documentation>
622 Change the documentation string associated with the attribute.
626 Change if the attribute lazily initializes the slot.
630 You I<are> allowed to change the type, B<if and only if> the new type is a
631 subtype of the old type.
635 You are allowed to B<add> a new C<handles> definition, but you are B<not>
636 allowed to I<change> one.
640 =item B<before $name|@names =E<gt> sub { ... }>
642 =item B<after $name|@names =E<gt> sub { ... }>
644 =item B<around $name|@names =E<gt> sub { ... }>
646 This three items are syntactic sugar for the before, after, and around method
647 modifier features that L<Class::MOP> provides. More information on these may be
648 found in the L<Class::MOP::Class documentation|Class::MOP::Class/"Method
653 The keyword C<super> is a no-op when called outside of an C<override> method. In
654 the context of an C<override> method, it will call the next most appropriate
655 superclass method with the same arguments as the original method.
657 =item B<override ($name, &sub)>
659 An C<override> method is a way of explicitly saying "I am overriding this
660 method from my superclass". You can call C<super> within this method, and
661 it will work as expected. The same thing I<can> be accomplished with a normal
662 method call and the C<SUPER::> pseudo-package; it is really your choice.
666 The keyword C<inner>, much like C<super>, is a no-op outside of the context of
667 an C<augment> method. You can think of C<inner> as being the inverse of
668 C<super>; the details of how C<inner> and C<augment> work is best described in
669 the L<Moose::Cookbook>.
671 =item B<augment ($name, &sub)>
673 An C<augment> method, is a way of explicitly saying "I am augmenting this
674 method from my superclass". Once again, the details of how C<inner> and
675 C<augment> work is best described in the L<Moose::Cookbook>.
679 This is the C<Carp::confess> function, and exported here because I use it
680 all the time. This feature may change in the future, so you have been warned.
684 This is the C<Scalar::Util::blessed> function, it is exported here because I
685 use it all the time. It is highly recommended that this is used instead of
686 C<ref> anywhere you need to test for an object's class name.
690 =head1 UNIMPORTING FUNCTIONS
694 Moose offers a way to remove the keywords it exports, through the C<unimport>
695 method. You simply have to say C<no Moose> at the bottom of your code for this
696 to work. Here is an example:
701 has 'first_name' => (is => 'rw', isa => 'Str');
702 has 'last_name' => (is => 'rw', isa => 'Str');
706 $self->first_name . ' ' . $self->last_name
709 no Moose; # keywords are removed from the Person package
711 =head1 EXTENDING AND EMBEDDING MOOSE
713 Moose also offers some options for extending or embedding it into your own
714 framework. The basic premise is to have something that sets up your class'
715 metaclass and export the moose declarators (C<has>, C<with>, C<extends>,...).
722 my $CALLER = caller();
727 # we should never export to main
728 return if $CALLER eq 'main';
729 Moose::init_meta( $CALLER, 'MyFramework::Base' );
730 Moose->import({into => $CALLER});
732 # Do my custom framework stuff
739 Moose's C<import> method supports the L<Sub::Exporter> form of C<{into =E<gt> $pkg}>
740 and C<{into_level =E<gt> 1}>
742 =head2 B<init_meta ($class, $baseclass, $metaclass)>
744 Moose does some boot strapping: it creates a metaclass object for your class,
745 and then injects a C<meta> accessor into your class to retrieve it. Then it
746 sets your baseclass to Moose::Object or the value you pass in unless you already
747 have one. This is all done via C<init_meta> which takes the name of your class
748 and optionally a baseclass and a metaclass as arguments.
756 It should be noted that C<super> and C<inner> B<cannot> be used in the same
757 method. However, they may be combined within the same class hierarchy; see
758 F<t/014_override_augment_inner_super.t> for an example.
760 The reason for this is that C<super> is only valid within a method
761 with the C<override> modifier, and C<inner> will never be valid within an
762 C<override> method. In fact, C<augment> will skip over any C<override> methods
763 when searching for its appropriate C<inner>.
765 This might seem like a restriction, but I am of the opinion that keeping these
766 two features separate (yet interoperable) actually makes them easy to use, since
767 their behavior is then easier to predict. Time will tell whether I am right or
768 not (UPDATE: so far so good).
772 =head1 ACKNOWLEDGEMENTS
776 =item I blame Sam Vilain for introducing me to the insanity that is meta-models.
778 =item I blame Audrey Tang for then encouraging my meta-model habit in #perl6.
780 =item Without Yuval "nothingmuch" Kogman this module would not be possible,
781 and it certainly wouldn't have this name ;P
783 =item The basis of the TypeContraints module was Rob Kinyon's idea
784 originally, I just ran with it.
786 =item Thanks to mst & chansen and the whole #moose poose for all the
787 early ideas/feature-requests/encouragement/bug-finding.
789 =item Thanks to David "Theory" Wheeler for meta-discussions and spelling fixes.
797 =item L<http://www.iinteractive.com/moose>
799 This is the official web home of Moose, it contains links to our public SVN repo
800 as well as links to a number of talks and articles on Moose and Moose related
803 =item L<Class::MOP> documentation
805 =item The #moose channel on irc.perl.org
807 =item The Moose mailing list - moose@perl.org
809 =item Moose stats on ohloh.net - L<http://www.ohloh.net/projects/5788>
811 =item Several Moose extension modules in the L<MooseX::> namespace.
819 =item L<http://www.cs.utah.edu/plt/publications/oopsla04-gff.pdf>
821 This paper (suggested by lbr on #moose) was what lead to the implementation
822 of the C<super>/C<override> and C<inner>/C<augment> features. If you really
823 want to understand them, I suggest you read this.
829 All complex software has bugs lurking in it, and this module is no
830 exception. If you find a bug please either email me, or add the bug
835 Stevan Little E<lt>stevan@iinteractive.comE<gt>
837 B<with contributions from:>
843 Anders (Debolaz) Nor Berle
845 Nathan (kolibre) Gray
847 Christian (chansen) Hansen
849 Hans Dieter (confound) Pearcey
851 Eric (ewilhelm) Wilhelm
853 Guillermo (groditi) Roditi
855 Jess (castaway) Robinson
859 Robert (phaylon) Sedlacek
863 Scott (konobi) McWhirter
865 Shlomi (rindolf) Fish
867 Yuval (nothingmuch) Kogman
869 Chris (perigrin) Prather
871 Jonathan (jrockway) Rockway
873 Piotr (dexter) Roszatycki
879 ... and many other #moose folks
881 =head1 COPYRIGHT AND LICENSE
883 Copyright 2006, 2007 by Infinity Interactive, Inc.
885 L<http://www.iinteractive.com>
887 This library is free software; you can redistribute it and/or modify
888 it under the same terms as Perl itself.